A. Field of Invention
The present invention relates to the field of engine starters and, more specifically, to a spring recoil starter used to facilitate the start of an internal combustion engine.
B. Description of the Related Art
It is known to use recoil starters to assist in the starting of small internal combustion engines. Such recoil starters are typically activated when an operator pulls a starter rope that is operatively connected to the starter. Generally, the operator must exert a fair amount of energy to overcome the compression force of the engine piston in order to start the engine. Once the operator pulls the starter rope, the rope or handle is then returned back to the starter housing via a rope return spring. This type of starter has two distinct disadvantages: 1) As previously mentioned the operator must exert a certain amount of energy or force to overcome the compression force of the piston in order to start the engine; 2) The compression force of the piston creates a jerking motion that is typically felt by the operator.
There have been several proposed methods to overcome the above-mentioned disadvantages. One such method, discussed in U.S. Pat. No. 5,537,966 to Ohnishi employs a power storage type of recoil starter that uses spiral springs to assist in starting the internal combustion engine. The Ohnishi patent the operator repeatedly pulls the starter rope to wind the spiral springs thereby storing energy in the spiral springs wherein this energy is then used to start the engine. As the operator continues to pull on the rope, the spiral springs continue to wind and the tension is held on the springs by a ratcheting locking mechanism thereby preventing the springs from unwinding. Once a sufficient amount of tension is on the springs, a releasing mechanism releases the ratcheting mechanism thereby releasing the stored energy in the springs so that the starter is rotated at a high speed to start the engine. There are several disadvantages to this type of system. First, the operator must pull the rope multiple times in order to wind the springs in order to create enough tension on the springs to overcome the compression force of the piston. The ratcheting system also requires more parts, which in turn is more expensive to manufacture. In addition, if the engine does not start after several pulls, energy is still stored in the spiral springs. If the operator leaves the device alone, any type of external force applied to the engine could disengage the ratcheting mechanism thereby releasing the energy in the springs, which in turn then can start the engine.
Other known prior art methods include those discussed in U.S. Pat. No. 4,543,922 to Fugazza et al. and U.S. Pat. No. 4,441,466 to Tangorra. Both of these patents employ an elastomeric material to store energy to facilitate the starting of the internal combustion engine. The disadvantage to this type of a starting mechanism is that in order to overcome the compression force of the piston, the elastomeric material must be of substantial size to overcome the force. This defeats the purpose of designing a compact starter for use in small engine applications, such as those on hand held string trimmers. In addition, both of these patents employ an external ratcheting or locking mechanism to prevent the elastomeric material from releasing prior to reaching its desired tension. Both of these ratcheting or locking mechanisms require an external force by the operator to start the engine.
Accordingly, one of the primary objectives of the present invention is to create a solution for the problems described above. The present invention overcomes the aforementioned disadvantages by employing a starter spring to assist the operator in starting the internal combustion engine. As the operator pulls the starter rope, the starter spring winds and accumulates tension until it overcomes the compression force of the piston, at which time the starter spring will unwind thereby rotating the engine thereby starting the engine. The diameter of the rope pulley and the length of the starter rope, as well as the size and strength of the starter spring are designed such that only one pull of the rope will start the engine.
It is therefore one object of the present invention to provide a starter for an internal combustion engine to allow the operator to easily start the engine with little effort.
It is another object of the present invention to provide an internal combustion engine to be used in small engine applications, such as those used on hand held string trimmers.
It is yet another object of the present invention to provide a starter that will increase the safety of the operators of the machines, which make use of the starter.
It is yet another object of the present invention to provide a starter for use on an internal combustion engine that will meet the strict EPA restrictions requiring low CO2 and NOX emissions.
Finally, it is yet another object of the present invention to provide a starter on an internal combustion engine that eliminates the jerking sensation during the starting process felt by the operator on conventional starters.